Other Parts Discussed in Thread: TINA-TI
Tool/software: TINA-TI or Spice Models
Hi,
Below is a gate driving circuit for a high-side N-Channel MOSFET switch using discrete components.
This circuit consist of two seperate stages: a Bootstrap circuit (for boosting the gate voltage) and a transistor Totem pole stage for high speed switching.
This circuit successfully switches the MOSFET to 11.92V (Vcc = 12V) but I cannot manage to get it to discharge all the way down to 0V. The lowest I get it is: 3.94V.
VG1 is a 500kHz Sqaure Wave with amplitude: 2.5V, DC level @ 0V.
Below is the Transient Analysis for this circuit.
Can someone please assist with what the problem might be? It should be noted that I get the same results when switching at 100kHz, 200kHz and 500kHz (as well as frequencies well below 100kHz) so this doesn't seem to be the problem.
Any assistance would be greatly appreciated.
(Please don't suggest an integrated MOSFET driver IC as this would defeat the purpose :) ).